US3706926A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for testing batch fabricated magnetic heads during manufacture utilizing magnetic fields generated by other magnetic heads
Assignee: International Business Machines Corp
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Filing: 1971-06-04
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Granted: 1972-12-19
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Expires: 1991-06-04
Abstract
Abstract Magnetic head elements are batch fabricated on areas of a substrate. During manufacture, and before final separation and processing of the areas into discrete multi-track magnetic heads, defective areas are identified for removal. An electric signal source subjects the head areas to a magnetic field which is detected as electric current in each head area. The detected current value in acceptable head areas falls within a predefined range. All head areas having a current outside the range are defined as defective. The magnetic field emanates from one set of head areas in the vicinity of another set of head areas being tested.
Inventors
- 👤 Stephen M Barrager
- 👤 Geoffrey Bate
- 👤 Sidney H Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:00
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/3109; G11B5/313; G11B5/3133; G11B5/314; G11B5/3163; G11B5/3166; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49004; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036; Y10T29/49043; Y10T29/49046; Y10T29/49048
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
165 words
In a combination for testing a plurality of magnetic head elements, arranged on a substrate, during manufacture and prior to separation and final processing, wherein the combination includes: drive circuits, connectable to one or more magnetic head elements and responsive to a drive current, for causing said elements to generate magnetic fields; detection circuits connectable to one or more magnetic head elements for monitoring, as electric signals, the magnetic field caused by said drive circuits; control means, interconnecting said drive and detection circuits with the head elements for initially enabling the drive circuits to supply current to a selected number of elements and the detection circuits to initially monitor a selected number of different elements; a source of electric current, indicative of acceptable values of current; an interpreter, associated with said detection circuit and source for comparing the monitored electric currents to acceptable values of currents; and indicating means, connected to said interpreter for indicating when the monitor and acceptable currents bear a predetermined relationship.
Claim 2
Dependent Claim
165 words
In a combination for testing a plurality of magnetic head elements, arranged on a substrate, during manufacture and prior to separation and final processing, wherein the combination includes: drive circuits, connectable to one or more magnetic head elements and responsive to a drive current, for causing said elements to generate magnetic fields; detection circuits connectable to one or more magnetic head elements for monitoring, as electric signals, the magnetic field caused by said drive circuits; control means, interconnecting said drive and detection circuits with the head elements for initially enabling the drive circuits to supply current to a selected number of elements and the detection circuits to initially monitor a selected number of different elements; a source of electric current, indicative of acceptable values of current; an interpreter, associated with said detection circuit and source for comparing the monitored electric currents to acceptable values of currents; and indicating means, connected to said interpreter for indicating when the monitor and acceptable currents bear a predetermined relationship.
Claim 3
Dependent Claim
32 words
The combination of claim 1 wherein the control means is additionally operable to subsequently cause the detection circuits to monitor initially driven elements and the drive circuits to drive initially monitored elements.
Claim 4
Dependent Claim
31 words
The combination of claim 2 wherein the head elements are arranged in rows and the drive circuits and detection circuits are, at any one time, connected to elements in different rows.
Claim 5
Dependent Claim
166 words
In a combination for testing a plurality of magnetic head elements, arranged on a substrate, during manufacture and prior to separation and final processing, wherein the combination includes: first circuits, connectable to one or more magnetic head elements and responsive to an input signal for generating fields from said elements; second circuits connectable to one or more magnetic head elements for monitoring, as output signals, the field caused by said first circuits; control means, interconnecting said first and second circuits with the head elements for enabling the first circuits to supply input signals to a selected number of elements and the second circuits to monitor a selected number of elements other than those elements connected to the first circuits; a source of test signals, indicative of acceptable values of output signals; an interpreter, associated with said second circuits and source for comparing the output and test signals; and indicating means, connected to said interpreter for indicating when the output and test signals bear a predetermined relationship.
Claim 6
Dependent Claim
166 words
In a combination for testing a plurality of magnetic head elements, arranged on a substrate, during manufacture and prior to separation and final processing, wherein the combination includes: first circuits, connectable to one or more magnetic head elements and responsive to an input signal for generating fields from said elements; second circuits connectable to one or more magnetic head elements for monitoring, as output signals, the field caused by said first circuits; control means, interconnecting said first and second circuits with the head elements for enabling the first circuits to supply input signals to a selected number of elements and the second circuits to monitor a selected number of elements other than those elements connected to the first circuits; a source of test signals, indicative of acceptable values of output signals; an interpreter, associated with said second circuits and source for comparing the output and test signals; and indicating means, connected to said interpreter for indicating when the output and test signals bear a predetermined relationship.
Claim 7
Dependent Claim
27 words
The combination of claim 4 wherein the control means is additionally operable to subsequently cause the first and second circuits to be connected to each others'' elements.
Claim 8
Dependent Claim
31 words
The combination of claim 5 wherein the head elements are arranged in rows and the first circuit and second circuits are, at any one time, connected to elements in different rows.
Claim 9
Independent Claim
85 words
The method for testing, during manufacture, batch-fabricated magnetic transducer elements on a surface, including the steps of: connecting a source of electric signals to a number of first elements; generating a magnetic field, intersecting other elements as a result of the electric signals; connecting means for detecting electric signals to a number of second elements intersected by the magnetic field; comparing the detected electric signals to reference limits; and identifying those elements having a detected signal within the reference limits and those outside the limits.
Claim 10
Independent Claim
85 words
The method for testing, during manufacture, batch-fabricated magnetic transducer elements on a surface, including the steps of: connecting a source of electric signals to a number of first elements; generating a magnetic field, intersecting other elements as a result of the electric signals; connecting means for detecting electric signals to a number of second elements intersected by the magnetic field; comparing the detected electric signals to reference limits; and identifying those elements having a detected signal within the reference limits and those outside the limits.
Claim 11
Dependent Claim
32 words
The method of claim 7 wherein there is the additional step of: reversing the connections to connect the electric signals to the second elements and to detect signals from the first elements.
Claim 12
Independent Claim
102 words
The method for testing, during manufacture, batch-fabricated magnetic Transducers formed on a surface as discrete elements having at least one magnetic and one conductive layer, including the steps of: connecting a source of electric signals to the conductive layers of a number of first elements; generating a magnetic field, intersecting the conductive layers of second elements as a result of the electric signals; detecting electric signals from a number of second elements intersected by the magnetic field; comparing the detected electric signals to reference limits; and identifying those elements having a detected signal within the reference limits and those outside the limits.
Claim 13
Independent Claim
102 words
The method for testing, during manufacture, batch-fabricated magnetic Transducers formed on a surface as discrete elements having at least one magnetic and one conductive layer, including the steps of: connecting a source of electric signals to the conductive layers of a number of first elements; generating a magnetic field, intersecting the conductive layers of second elements as a result of the electric signals; detecting electric signals from a number of second elements intersected by the magnetic field; comparing the detected electric signals to reference limits; and identifying those elements having a detected signal within the reference limits and those outside the limits.
Claim 14
Dependent Claim
32 words
The method of claim 9 wherein there is the additional step of: reversing the connections to connect the electric signals to the second elements and to detect signals from the first elements.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-19 | 1976-06-19 | 1976-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-19 | 1980-06-19 | 1980-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-19 | 1984-06-19 | 1984-12-19 | $7700.00 | Window Closed / Lapsed |